Depositions on chamber members (e.g., walls, shields, windows, etc.) are an important issue in the semiconductor manufacturing process as these depositions can be a source of particle generation or alter the process plasma and thus can affect process conditions. Periodic cleaning of chamber member depositions in a chamber is therefore a necessary part of the semiconductor manufacturing process. In some cases there can be excessive cleaning of the chamber, where not only the deposition but some of the chamber itself is eroded. Presently, there are no systems that perform in situ measurement of the deposition on the chamber or direct measurement of the removal of the film or chamber erosion.
Therefore, it is an object of the present invention to provide a sensor that can perform in-situ measurement of the thickness of chamber member deposition to determine if a cleaning process is required, when a cleaning process has been completed and when chamber erosion has occurred. It is also an object of the present invention to provide temperature compensation techniques that allow the sensor to yield reliable film thickness measurements for the wide range of temperatures that can occur in a reactor chamber.